Commonly used fluorescent light source enclosures of the types currently used for illumination in underground mines, e.g. on mining equipment for illuminating the vicinity of a mining activity, generally is generally elongated-cylindrical in shape. A now-typical device is shown in the copending U.S. patent application of McJunkin, Jr., et al., Ser. No. 736,204, filed Oct. 27, 1976, now U.S. Pat. No. 4,247,884, issued Jan. 27, 1981 and in the U.S. patent of Dacal, U.S. Pat. No. 4,042,819, issued Aug. 16, 1977.
While the specific design of lighting enclosure varies from manufacturer to manufacturer, the basic shape necessitates that such enclosures be mounted on an exterior surface as an outward protrusion therefrom in order to take full advantage of their light output. That limitation necessitates that these prior art lighting enclosures be relatively highly exposed to threat of damage from collision between relatively moving structures, one of which is such a lighting device protruding from the structure on which it is mounted. If an attempt is made to recess such lighting fixtures in order to protect them from damage and/or to minimize the overall size of the machine so it can work in smaller spaces sacrifices light output--and it virtually eliminates easy servicing. That is so because these prior art enclosures are designed to be serviced through one end. Any recessing tends to prevent the easy access to those ends which users often find is essential.
The present applicant has previously invented and participated in the design of a side-access, triangular housing for bulb-type light sources. These are disclosed in the copending U.S. patent applications of McJunkin, Jr., Ser. No. 818,664, filed July 25, 1975, now U.S. Pat. No. 4,158,880, issued June 19, 1979, and McJunkin, Jr., et al., Ser. No. 800,436, filed May 25, 1977, now U.S. Pat. No. De. 250,970, issued Jan. 30, 1979. Some of the favorable attributes of the present invention, compared to the prior art cylindrical enclosures for fluorescent lamp tubes, are ones it shares with this prior art triangular housing for bulb-type light sources.